The present invention relates to a circuit for controlling point-generating units of the write-head of a printer, said circuit constituting an interface between a central unit, an external direct access memory and a driver which activates the write head. The novel circuit is configured to manage real-time tasks and tasks which would place an excessively high load on the central unit of a printer of this kind.
In order to obtain standardized software relating to the printer concerned, it is necessary to dispose the pixel data in vertical columns, irrespective of the physical dimensions of the write head. The conversion required herefor is thus handled by the control circuit, since a software converter would consume too much central-unit time. Synchronization of the print to a given position on the rows constitutes a real-time task. This is taken care of by the control circuit, which can use a clock signal from an external signal source or a linear position sensor having two or three phases for synchronizing print with the movement of the write head.
In the case of conventional printer write-heads, the point-generating units often comprise so-called write-head needles. These needles are normally arranged linearly in the write head and perpendicular to a row to be printed. In order to cover the maximum height of a print character, i.e. a full row division, the needles must, in this case, be placed very close together.
This places great demands on tolerances and material selection, which naturally leads to high manufacturerelated costs.